You don't need to be a photography expert to know that camera shake can ruin a photo. Avoiding camera shake can be difficult, whether trying to capture intricate detail in artwork or simply trying to capture an image of text that isn't too blurry to read later. The iPhone is small enough and light enough that just a slight push on the volume button or even the virtual shutter button can ruin a photo. The new jailbreak tweak ProximityCam, from developer PoomSmart, offers a practical solution to the problem.
ProximityCam allows you to use the iPhone's proximity sensor (the sensor that turns the screen off when you hold it up to your ear in order to save power and avoid inadvertent input) to take photographs. With ProximityCam installed you simply wave your finger in front of the sensor to take a picture with the Camera app. This
allows you to find your desired focus and then take the picture without any additional touching that could cause camera shake and alter the focus. You could, in fact, take a photo without touching the phone at all.
The tweak works with both the rear and forward facing cameras, though keep in mind that the proximity sensor is very close to the forward facing camera. Also, ProximityCam currently works with the camera in landscape mode only if the camera has been accessed through the lock screen.ProximityCam also comes with a preference pane that can be accessed via Settings -> ProximityCam. There are a few options here - you can enable/disable the tweak and you can enable/disable the dim function of the proximity sensor. You probably don't want the screen dimming while you are trying to take pictures. You can also set the "Capture Interval," which lets you adjust how often the camera will take pictures. For example, you could have it take several shots with one wave of your finger rather than just one.
ProximityCam is available for free from Cydia's BigBoss repository. It requires a jailbroken iPhone and iOS 7 or better.